The present invention relates to a device having a group of tubes arranged between two tube plates and provided with expansion bends for heat exchange between a fluid circulating within the tubes and a liquid circulating around the tubes.
The expansion bends of such devices can be caused to vibrate for certain flow rates of the fluid circulating around the tubes, particularly when this fluid is a liquid alkali metal. If the excitation frequency due to the fluid flow is close to the resonant frequency of the expansion bends, the vibrations which occur can be sufficient to seriously damage the tubes.
For obviating this phenomenon it has already been proposed to place the expansion bends in an area where they are not in contact with the flowing fluids, for example when the latter is a liquid alkali metal, in a zone filled with a rare gas surmounting the bath of said metal, in the vicinity of the tube plate of the hot end of the exchanger.
However, this often leads to an increase in the length of the group of tubes, which is often already very long, the length of the expansion bends not being involved in the heat exchange. Moreover, the expansion bends are located in the hottest part of the exchanger, where the permitted work rate is lowest.